(a) Field of the Invention
The present invention relates to a lateral flow atomic layer deposition apparatus and a method of depositing a thin film using the same.
(b) Description of the Related Art
In fabricating a semiconductor device, an effort to improve an apparatus or a process for forming a thin film with high quality on a substrate has been made. Nowadays, an atomic layer deposition (ALD) method to grow a thin film on a substrate is suggested where a thin film is formed on a substrate through a surface reaction by supplying two or more reactants separately and sequentially to the substrate, and a thin film with a desired thickness is obtained by repeating the sequential process mentioned above. Because a film is formed by a surface reaction, when using such a process, a thin film is deposited uniformly across the entire surface of the substrate regardless of protrusions and depressions of the substrate, and impurities in the film can be minimized such that a high quality thin film can be formed.
There are many types of ALD apparatus. In particular, a lateral flow atomic layer deposition reactor in which a gas flows in a direction parallel to a substrate provides fast gas switching since the gas flow is simple in the lateral flow atomic layer deposition reactor. Korean patent No. 624,030 and its corresponding U.S. Pat. No. 6,539,891 show a lateral flow ALD reactor. Since the volume of the reactor described in the above-identified patents is small enough to switch gases fast, the gas switching time for atomic layer deposition can be minimized, thus achieving high productivity. Further, their advanced structure is disclosed in Korean Patent Application No. 2007-7027238 and U.S. patent application Ser. No. 11/429,533. In this reactor, a plasma ALD method can be performed by supplying radio frequency (RF) power to the reaction space sequentially in accordance with a gas supply cycle.
Another example of a lateral flow atomic layer deposition reactor is disclosed in U.S. Pat. No. 5,711,811 and U.S. Pat. No. 6,562,140 in which a gap between a substrate surface and a surface opposite to the substrate is maintained constantly to make gas flow uniform such that the gas flow is maintained similarly to laminar flow on the substrate.
However, a lateral flow reactor has a problem because the difference in film uniformity on a substrate near a gas inlet and a gas outlet is large. Such a problem may be improved by rotating the substrate, however, it is not an easy task due to the complexity of a structure for rotating the substrate thereof, and difficulty in setting a process condition for rotating the substrate. Further, there have been efforts to solve such non-uniformity issue by changing a direction of a gas flow on the substrate (for example, see U.S. Pat. No. 6,806,211; U.S. Pat. No. 7,020,981; and U.S. Patent No. 2009/0217873). However, these patents failed to suggest a compact structure that is optimized for an ALD process.
The above information disclosed in this Background section is only for enhancing the understanding of the background of the invention, and therefore it may contain information that does not form the prior art that is already known in this country to a person of ordinary skill in the art.